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Abstract:

To provide a cosmetic composition and a hair wash which are excellent in
metal pyrithione salt persistence after washing with a washing liquid
containing a surfactant, etc.
A cosmetic composition and a hair wash, which comprise a copolymer and a
metal pyrithione salt, wherein the copolymer contains constituting units
corresponding to a cationic vinyl monomer of a specific structure and
constituting units corresponding to a nonionic vinyl monomer of a
specific structure.

Claims:

1. A cosmetic composition comprising a cationic polymer and a metal
pyrithione salt, wherein the cationic polymer has a cationic group and at
least one group selected from a hydroxy group and an amide group having
only a nonionic substituent; the amount of the cationic group is from 0.1
to 10.0 meq/g; at least one of the amount of the hydroxy group being from
1.5 to 20.0 meq/g and the amount of the amide group having only a
nonionic substituent being from 1.5 to 10.0 meq/g, is satisfied; and when
the cosmetic composition is used as a hair wash, the amount of adsorption
of the metal pyrithione salt is at least 20 μg/g on at least one of
untreated hair and damaged hair.

2. A cosmetic composition comprising a copolymer (1) and a metal
pyrithione salt, wherein the copolymer contains constituting units
corresponding to a cationic vinyl monomer (A) represented by the
following formula (I) and constituting units corresponding to a nonionic
vinyl monomer (B) represented by the following formula (II) and/or (III);
the proportion of the constituting units corresponding to the cationic
vinyl monomer (A) is from 10 to 80 wt % to the total constituting units
constituting the copolymer; and the weight average molecular weight of
the copolymer is from 10,000 to 2,000,000:
CH.sub.2.dbd.C(R1)--CO(O)a--(NH)1-a--(CH2)b--N.s-
up.+R2R3R.sup.4.X.sup.- (I) (wherein R1 is a hydrogen atom
or a methyl group, each of R2 and R3 which are independent of
each other, is a C1-24 alkyl group, a C1-24 aryl group or a
C1-24 aralkyl group, R4 is a hydrogen atom, a C1-24 alkyl
group, a C1-24 aryl group, a C1-24 aralkyl group or
--CH2--CH(OH)--CH2--N+R5R6R7Y.sup.-, each
of R5 to R7 which are independent of one another, is a
C1-24 alkyl group, a C1-24 aryl group or a C1-24 aralkyl
group, each of X.sup.- and Y.sup.- which are independent of each other,
is an anion, a is 0 or 1, and b is an integer of from 1 to 10)
CH.sub.2.dbd.C(R8)--CO(O)--X--H (II) (wherein R8 is a hydrogen
atom or a methyl group, and X is a bivalent linking group containing at
least two hydroxy groups) CH.sub.2.dbd.C(R9)--CO--NR10R11
(III) (wherein R9 is a hydrogen atom or a methyl group, and each of
R10 and R11 which are independent of each other, is a hydrogen
atom, a C1-4 alkyl group or a C1-4 hydroxyalkyl group).

3. The cosmetic composition according to claim 1, wherein the metal
pyrithione salt is zinc pyrithione.

4. The cosmetic composition according to claim 2, wherein the metal
pyrithione salt is zinc pyrithione.

5. The cosmetic composition according to claim 1, which further contains
an anion surfactant.

6. The cosmetic composition according to claim 2, which further contains
an anion surfactant.

7. The cosmetic composition according to claim 3, which further contains
an anion surfactant.

8. The cosmetic composition according to claim 4, which further contains
an anion surfactant.

9. A hair wash employing the cosmetic composition as defined in claim 1.

10. A hair wash employing the cosmetic composition as defined in claim 2.

11. A hair wash employing the cosmetic composition as defined in claim 3.

12. A hair wash employing the cosmetic composition as defined in claim 4.

13. A hair wash employing the cosmetic composition as defined in claim 5.

14. A hair wash employing the cosmetic composition as defined in claim 6.

15. A hair wash employing the cosmetic composition as defined in claim 7.

16. A hair wash employing the cosmetic composition as defined in claim 8.

Description:

TECHNICAL FIELD

[0001] The present invention relates to a cosmetic composition and a hair
wash, which comprise a copolymer of a specific structure and a metal
pyrithione salt.

BACKGROUND ART

[0002] It is already well known to incorporate a metal pyrithione salt as
represented by zinc pyrithione in a cosmetic composition, and when it is
incorporated in a hair wash such as a shampoo, it is possible to
effectively control formation of dandruff. It is known that such an
anti-dandruff effect is brought about by the metal pyrithione salt which
remains on the scalp or hair after washing, and its persistence in the
washing process is substantially influential over such an effect.
Therefore, a cosmetic composition showing a high persistence of a metal
pyrithione salt at the time of washing is desired.

[0005] However, the anti-dandruff particle persistence shown in Patent
Document 1 was not sufficient, and a further improvement in the
anti-dandruff effect has been desired.

[0006] Further, it is extremely difficult to simultaneously attain letting
a hardly water-soluble dispersed material such as a metal pyrithione salt
having an anti-dandruff effect stay on the hair and removing dirt such as
oil and dust from the hair or scalp, which is the intended purpose of the
hair wash. Further, in a case where a conventional polymer as disclosed
in Patent Document 1 was used for a cosmetic application, the effect for
adsorption of a metal pyrithione salt such as zinc pyrithione was not
sufficient.

[0007] As a method to overcome such a problem, it is conceivable to
incorporate a large amount of an anti-dandruff agent such as a metal
pyrithione salt, particularly zinc pyrithione, to the hair wash, but such
a method is likely to bring about deterioration of the touch such as
smoothness after the use, by the incorporation of a large amount of the
anti-dandruff agent, or is likely to lead to environmental pollution such
that a waste liquid containing a large amount of the anti-dandruff agent
is discharged after the use of the hair wash.

[0008] It is an object of the present invention to solve such a problem
and to provide a cosmetic composition which is capable of improving the
metal pyrithione salt persistence after washing by a washing liquid
containing a surfactant, etc. and which is capable of exhibiting a
sufficient anti-dandruff effect by using only a small amount of a metal
pyrithione salt. In addition, it is an object of the present invention to
provide a hair wash which is made of such a composition and which is
excellent in both the anti-dandruff effect and the washing property to
remove dirt such as oil and dust from the hair or scalp and is also
excellent in the touch such as smoothness after the use.

Solution to Problem

[0009] In view of the above problem, the present inventors have conducted
an extensive study and as a result, have found that when a polymer having
a specific amount of a cationic group and a specific amount of a hydroxy
group and/or an amide group having only a nonionic substituent
(hereinafter these groups may be referred to as functional groups), is
incorporated, a metal pyrithione salt, particularly zinc pyrithione,
exhibits a high residual effect. Further, it has been found that a
cosmetic composition obtained by blending a metal pyrithione salt and a
copolymer containing constituting units corresponding to a cationic vinyl
monomer of a specific structure and constituting units corresponding to a
nonionic vinyl monomer of a specific structure, exhibits a high metal
pyrithione salt persistence. Thus, the present invention has been
accomplished.

[0010] Thus, the present invention provides the following (i) to (v).

[0011] (i) A cosmetic composition comprising a cationic polymer and a
metal pyrithione salt, wherein the cationic polymer has a cationic group
and at least one group selected from a hydroxy group and an amide group
having only a nonionic substituent; the amount of the cationic group is
from 0.1 to 10.0 meq/g; at least one of the amount of the hydroxy group
being from 1.5 to 20.0 meq/g and the amount of the amide group having
only a nonionic substituent being from 1.5 to 10.0 meq/g, is satisfied;
and when the cosmetic composition is used as a hair wash, the amount of
adsorption of the metal pyrithione salt is at least 20 μg/g on at
least one of untreated hair and damaged hair.

[0012] (ii) A cosmetic composition comprising a copolymer (1) and a metal
pyrithione salt, wherein the copolymer contains constituting units
corresponding to a cationic vinyl monomer (A) represented by the
following formula (I) and constituting units corresponding to a nonionic
vinyl monomer (B) represented by the following formula (II) and/or (III);
the proportion of the constituting units corresponding to the cationic
vinyl monomer (A) is from 10 to 80 wt % to the total constituting units
constituting the copolymer; and the weight average molecular weight of
the copolymer is from 10,000 to 2,000,000:

CH2═C(R1)--CO(O)a--(NH)1-a--(CH2)b--N.-
sup.+R2R3R4.X.sup.- (I)

(wherein R1 is a hydrogen atom or a methyl group, each of R2
and R3 which are independent of each other, is a C1-24 alkyl
group, a C1-24 aryl group or a C1-24 aralkyl group, R4 is
a hydrogen atom, a C1-24 alkyl group, a C1-24 aryl group, a
C1-24 aralkyl group or
--CH2--CH(OH)--CH2--NR5R6R7Y, each of R5 to
R7 which are independent of one another, is a C1-24 alkyl
group, a C1-24 aryl group or a C1-24 aralkyl group, each of
X.sup.- and Y.sup.- which are independent of each other, is an anion, a
is 0 or 1, and b is an integer of from 1 to 10)

CH2═C(R8)--CO(O)--X--H (II)

(wherein R8 is a hydrogen atom or a methyl group, and X is a
bivalent linking group containing at least two hydroxy groups)

CH2═C(R9)--CO--NR10R11 (III)

(wherein R9 is a hydrogen atom or a methyl group, and each of
R10 and R11 which are independent of each other, is a hydrogen
atom, a C1-4 alkyl group or a C1-4 hydroxyalkyl group).

[0013] (iii) The cosmetic composition according to the above (i) or (ii),
wherein the metal pyrithione salt is zinc pyrithione.

[0014] (iv) The cosmetic composition according to any one of the above (i)
to (iii), which further contains an anionic surfactant.

[0015] (v) A hair wash employing the cosmetic composition as defined in
any one of the above (i) to (iv).

Advantageous Effects of Invention

[0016] It is known that a metal pyrithione salt effectively prevents
dandruff. By using e.g. a hair wash having a metal pyrithione salt
incorporated, it is permitted to stay on the hair thereby to exhibits the
effect. The more the residual amount, the higher the anti-dandruff
effect. The cosmetic composition of the present invention is excellent
particularly in the metal pyrithione salt persistence after washing by a
washing liquid containing a surfactant, etc. Thus, it is possible to
exhibit a sufficient anti-dandruff effect by using only a small amount of
the metal pyrithione salt.

[0017] Especially in a case where the cosmetic composition of the present
invention is used as a washing liquid, it is possible to provide a
washing liquid which is excellent in both the anti-dandruff effect and
the washing property to remove dirt such as oil and dust from the body,
particularly from the hair or scalp and which is excellent in the touch
such as smoothness after the use.

DESCRIPTION OF EMBODIMENTS

[0018] Now, the present invention will be described in detail with
reference to its embodiments, as the following description of the
constituting elements relates to typical examples of embodiments of the
present invention, it should be understood that the present invention is
by no means thereby restricted.

[0019] In this specification, the "cationic group" means a functional
group containing a positively charged atom such as nitrogen of a
quaternary amine, and it may be in the form of a salt or in a state
ionized in a solution. Further, the "cationic monomer" and the "cationic
polymer" mean a monomer and polymer containing a positively charged atom,
respectively. Further, the "nonionic monomer" means an electrically
neutral monomer not containing an atom having an electric charge.
Further, "cationic" used in the above "cationic group", "cationic
polymer" or "cationic monomer" means not to contain a so-called
"amphoteric" one having both of an atom having a positive charge and an
atom having a negative charge.

[0020] In the present invention, the "amide group having only a nonionic
substituent" is meant for one wherein an electrically neutral substituent
is bonded directly to the nitrogen atom of an amide group, and in
Examples in this specification, an amide group having a hydroxyethyl
group bonded thereto, of HEAA, or an amide group having a methyl group
bonded thereto, of DMAA used in copolymers (i), (ii) and (vii),
corresponds thereto.

[0021] Further, in this specification, the "polymer" includes a polymer
derived from a natural product. Further, "(meth)acrylate" is a general
term for an acrylate and a metal acrylate. The same applies with respect
to "(meth)acrylamide" and "(meth)acrylic acid."

[0022] Further, in this specification, the expression "to" is used to
include the numerical values before and after "to" as the lower and
higher limit values.

<Cosmetic Composition)

[0023] The cosmetic composition of the present invention means an optional
cosmetic preparation to be used for the hair and skin, and it widely
includes so-called cosmetic preparations, such as a shampoo, a rinse, a
conditioner, a treatment, a hair coloring agent, a permanent wave agent,
an out-bath treatment, a hair pack, a hair spray, a hair foam, a styling
agent, a body shampoo, a make cleansing, a hand soap, a milky lotion, a
skin lotion, a lotion, a cream, a beauty essence, a sunscreen, a
foundation, a lip stick, a mascara, an eye shadow, a depilation agent,
etc. Further, the manner of its use may include one wherein it is applied
and well spread over the skin, hair, etc., followed by rinsing (washing
off) and one not followed by rinsing.

[0024] The cosmetic composition of the present invention is particularly
preferably used for the hair, and a hair wash made of the cosmetic
composition of the present invention is preferred as it is excellent in
the anti-dandruff effect. Here, the hair wash is one which is applied to
the hair and then rinsed off, and it may, for example, be a shampoo, a
rinse, a conditioner or a treatment. Improvement of the anti-dandruff
effect is attributable to improvement of the amount of adsorption of a
metal pyrithione salt to exhibit the anti-dandruff effect on the hair.

[0025] Usually, at the time of diluting a shampoo with water for the
purpose of making the touch smooth at the time of rinsing the shampoo
from the hair, it is necessary to design the composition of a polymer and
a hair cosmetic so that a water-insoluble precipitate (hereinafter
sometimes referred to as a complex) composed of a cationic polymer and a
surfactant, will form.

[0026] As a method to let a metal pyrithione salt (particularly zinc
pyrithione) as an anti-dandruff agent be substantially adsorbed on the
hair, it is conceivable (1) to let the precipitate take in the metal
pyrithione salt, or (2) to let the precipitate be substantially adsorbed
on the hair during rinsing.

[0027] As a specific method for (1) (as a method for letting the
precipitate take in a large amount of the metal pyrithione salt), it is
effective to increase the interaction of a copolymer to a metal ion as a
constituting component of the metal pyrithione salt and for example, it
is considered preferred to obtain a large amount of e.g. a hydroxy group
having a chelate effect, as a constituting unit of the copolymer.

[0028] Further, as a specific method for (2) (as a method for letting the
precipitate be substantially adsorbed on the hair at the time of
rinsing), it may, for example, be mentioned that the copolymer has a
suitable amount of a cationic group or a structural flexibility, or the
copolymer has a structure having a high affinity to the hair surface. For
the precipitate to satisfy such conditions, it is conceivable, for
example, to control the amount of a cationic group by the amount of
constituting units of the polymer, to use an acrylic resin for the main
chain of the copolymer to let the structure have flexibility, or to adopt
a structure having a hydrogen-bonding property, such as an amide group,
to increase the affinity to the hair.

[0029] In view of the foregoing, the first cosmetic composition of the
invention is a cosmetic composition comprising a cationic polymer and a
metal pyrithione salt, wherein the cationic polymer has a cationic group
and at least one group selected from a hydroxy group and an amide group
having only a nonionic substituent; the amount of the cationic group is
from 0.1 to 10.0 meq/g; at least one of the amount of the hydroxy group
being from 1.5 to 20.0 meq/g and the amount of the amide group having
only a nonionic substituent being from 1.5 to 10.0 meq/g, is satisfied.
And when the cosmetic composition is used as a hair wash, the amount of
adsorption of the metal pyrithione salt is at least 20 μg/g on at
least one of untreated hair and damaged hair.

[0030] Further, the second cosmetic composition of the invention is a
cosmetic composition comprising a copolymer (1) and a metal pyrithione
salt, wherein the copolymer contains constituting units corresponding to
a cationic vinyl monomer (A) represented by the following formula (I) and
constituting units corresponding to a nonionic vinyl monomer (B)
represented by the following formula (II) and/or (III); the proportion of
the constituting units corresponding to the cationic vinyl monomer (A) is
from 10 to 80 wt % to the total constituting units constituting the
copolymer; and the weight average molecular weight of the copolymer is
from 10,000 to 2,000,000.

CH2═C(R1)--CO(O)a--(NH)1-a--(CH2)b--N.-
sup.+R2R3R4.X.sup.- (I)

CH2 ═C(R8)--CO(O)--X--H (II)

CH2 ═C(R9)--CO--NR10R11 (III)

[0031] In the above formula (I), R1 is a hydrogen atom or a methyl
group, each of R2 and R3 which are independent of each other,
is a C1-24 alkyl group, a C1-24 aryl group or a C1-24
aralkyl group, R4 is a hydrogen atom, a C1-24 alkyl group, a
C1-24 aryl group, a C1-24 aralkyl group or
--CH2--CH(OH)--CH2--N+R5R6R7.Y.sup.-, each
of R5 to R7 which are independent of one another, is a
C1-24 alkyl group, a C1-24 aryl group or a C1-24 aralkyl
group, each of X.sup.- and Y.sup.- which are independent of each other,
is an anion, a is 0 or 1, and b is an integer of from 1 to 10. Further,
in the formula (II), R8 is a hydrogen atom or a methyl group, and X
is a bivalent linking group containing at least two hydroxy groups.
Further, in the formula (III), R9 is a hydrogen atom or a methyl
group, and each of R10 and R11 which are independent of each
other, is a hydrogen atom, a C1-4 alkyl group or a C1-4
hydroxyalkyl group.

<Cationic Polymer>

[0032] The cationic polymer to be used for the cosmetic composition of the
present invention is one having a cationic group, and the upper limit of
the amount of the cationic group is usually 10.0 meq/g, preferably 5.0
meq/g, and the lower limit is usually 0.1 meq/g, preferably 0.4 meq/g. If
the amount of the cationic group is larger than 10.0 meq/g, the
formulation property tends to be deteriorated, such that when a shampoo
is formulated, aggregates are likely to be formed, and if it is smaller
than 0.1 meq/g, the adsorption property on the hair tends to be low when
the composition is used as a hair wash.

[0033] The cationic polymer to be used for the cosmetic composition of the
present invention is required to contain, in its structure, at least one
functional group selected from a hydroxy group and an amide group having
only a nonionic substituent. The upper limit of the amount of the hydroxy
group is usually 20.0 meq/g, preferably 15.0 meq/g, particularly
preferably 10.0 meq/g, and the lower limit is usually 1.5 meq/g,
preferably 2.0 meq/g, particularly preferably 2.5 meq/g. Further, the
upper limit of the amount of the amide group having only a nonionic
substituent is usually 10.0 meq/g, preferably 8.0 meq/g, more preferably
6.0 meq/g, and the lower limit is usually 1.5 meq/g, preferably 2.0
meq/g, more preferably 2.5 meq/g.

[0034] The cationic polymer of the present invention is one which
satisfies at least one of the above amount of the hydroxy group and the
above amount of the amide group having only a nonionic substituent.
However, in a case where the cationic polymer is one not containing an
amide group having only a nonionic substituent, the amount of the hydroxy
group is preferably at least 4.2 meq/g in order to increase the effect
for adsorption of the metal pyrithione salt. If the amount of the hydroxy
group is larger than 20.0 meq/g or if the amount of the amide group
having only a nonionic substituent is larger than 10.0 meq/g, the
hydrophilicity of the copolymer tends to be high, and precipitates tend
to be hardly formed during rinsing. Further, if the amount of the hydroxy
group is smaller than 1.5 meq/g, and the amount of the amide group having
only a nonionic substituent is smaller than 1.5 meq/g, the amount of
adsorption of the metal pyrithione salt tends to be small.

[0035] Thus, the polymer contained in the cosmetic composition of the
present invention is one containing at least one of the hydroxy group and
the amide group having only a nonionic substituent, wherein the amount of
the hydroxy group is from 1.5 to 20.0 meq/g; the amount of the amide
group having only a nonionic substituent is from 1.5 to 10.0 meq/g; and
further, the amount of the cationic group is from 0.1 to 10.0 meq/g. In
this specification, the amount of each functional group represents the mg
equivalent of the functional group per 1 g of the cationic polymer and
can be determined or analyzed by various methods. However, it is simple
to regard it as the value of the charged amount at the time of
preparation of the polymer, and also in Examples of this application,
such a method is adopted.

[0036] The cationic polymer of the present invention is not particularly
limited, so long as it satisfies the above-mentioned amounts of the
respective functional groups, but specific examples may be a
cation-modified cellulose ether derivative, a cation-modified
galactomannan polysaccharide, a copolymer of a dimethyldiallylammonium
halide with acrylamide, a copolymer of a diallyldimethylammonium chloride
with vinyl pyrrolidone, a copolymer of a polymerizable vinyl monomer
containing a quaternary ammonium group, with various vinyl monomer, etc.

[0037] Further, as the above-mentioned copolymer of a polymerizable vinyl
monomer containing a quaternary ammonium group with various vinyl
monomer, a particularly preferred example may be a combination of one or
two among N-(meth)acryloyloxyethyl-N,N,N-trimethylammonium chloride and
N-(meth)acryloylaminopropyl-N,N,N-trimethylammonium chloride, and at
least one selected from the group consisting of N-hydroxyethylacrylamide,
N,N-dimethylacrylamide, 2,3-dihydroxypropyl methacrylate and
2-hydroxyethyl methacrylate.

[0038] Further, as the cationic polymer of the present invention, it is
also possible to use, other than those described above, one contained in
the copolymer (1) as described below, so long as it satisfies the amounts
of the respective functional groups. Further, the above-mentioned
cationic polymers may, respectively, be used alone, or two or more of
them may be used in combination.

<Copolymer (1)>

[0039] As the polymer to be used for the cosmetic composition of the
present invention, a copolymer (hereinafter sometimes referred to as
copolymer (1)) may be mentioned which contains constituting units
corresponding to a cationic vinyl monomer (A) represented by the formula
(I) and constituting units corresponding to a nonionic vinyl monomer (B)
represented by the formula (II) or (III).

[0040] The copolymer (1) contained in the cosmetic composition of the
present invention has a structure corresponding to a copolymer of a
monomer mixture comprising a vinyl monomer having a cationic group and a
nonionic vinyl monomer. That is, it is a copolymer containing
constituting units corresponding to a cationic vinyl monomer (A)
represented by the formula (I) (hereinafter sometimes referred to as the
cationic vinyl monomer (A)) and constituting units corresponding to a
nonionic vinyl monomer (B) represented by the formula (II) or (III)
(hereinafter sometimes referred to as the nonionic vinyl monomer (B)).

[0041] The cationic vinyl monomer (A) is not particularly limited so long
as it is a (meth)acrylic quaternary ammonium salt monomer represented by
the following formula (I), and it may, for example, be a (meth)acrylic
acid ester type quaternary ammonium salt such as
N-methacryloyloxyethyl-N,N,N-trimethylammonium chloride, or a
(meth)acrylamide type quaternary ammonium salt such as
N-methacryloylaminopropyl-N,N,N-trimethylammonium chloride.

CH2═C(R1)--CO(O)a--(NH)1-a--(CH2)b--N.-
sup.+R2R3R4.X.sup.- (I)

(wherein R1 is a hydrogen atom or a methyl group, each of R2
and R3 which are independent of each other, is a C1-24 alkyl
group, a C1-24 aryl group or a C1-24 aralkyl group, R4 is
a hydrogen atom, a C1-24 alkyl group, a C1-24 aryl group, a
C1-24 aralkyl group or
--CH2--CH(OH)--CH2--N+R5R6R7.Y.sup.-, each
of R5 to R7 which are independent of one another, is a
C1-24 alkyl group, a C1-24 aryl group or a C1-24 aralkyl
group, each of X.sup.- and Y.sup.- which are independent of each other,
is an anion, a is 0 or 1, and b is an integer of from 1 to 10.)

[0042] R1 is preferably a methyl group, and each of R2 and
R3 which are independent of each other, is preferably a C1-24
alkyl group, more preferably a methyl group or an ethyl group,
particularly preferably a methyl group. R4 is preferably a
C1-24 alkyl group, more preferably a methyl group, an ethyl group or
a butyl group, particularly preferably a methyl group. Each of R5 to
R7 which are independent of one another, is preferably a C1-24
alkyl group, more preferably a methyl group or an ethyl group,
particularly preferably a methyl group. Each of anions represented by
X.sup.- and Y.sup.- which are independent of each other, is preferably a
chlorine ion, an iodine ion or a bromine ion. b is preferably an integer
of from 1 to 5, more preferably 2 or 3.

[0045] Further, the constituting units corresponding to the cationic vinyl
monomer (A) of the copolymer (1) may be obtained, for example, by
polymerizing the above-described cationic vinyl monomer (A), or may
otherwise be obtained by copolymerizing a precursor of a cationic vinyl
monomer represented by the following formula (IV), followed by a
cationization reaction by means of a cationization agent to cationize the
copolymer to convert it to a structure having the corresponding cationic
group.

CH2═C(R1)--CO(O)a--(NH)1-a--(CH2)b--N.-
sup.+R2R3 (IV)

(wherein R1 to R3, a and b are as defined above in the above
formula (I), and the preferred ranges are also the same.)

[0046] The precursor of the cationic vinyl monomer may, for example, be a
(meth)acrylic acid ester having a tertiary amine structure, such as
N-(meth)acryloyloxyethyl-N,N-dimethylamine or
N-(meth)acryloyloxyethyl-N,N-diethylamine; or a (meth)acrylamide having a
tertiary amine structure, such as
N-(meth)acryloylaminopropyl-N,N-dimethylamine or
N-(meth)acryloylaminopropyl-N,N-diethylamine.

[0047] The cationization agent may, for example, be an alkyl halide such
as methyl chloride, or a cation group-containing cationization agent such
as 3-chloro-2-hydroxypropyl-N,N,N-trimethylammonium chloride. The
cationization reaction may be carried out, for example, by adding the
cationization agent to a solution of the copolymer under a condition of
from 20 to 100° C. for from 1 to 20 hours.

[0048] Further, as such a cationic vinyl monomer (A) or its precursor, one
type may be used alone or two or more types may be used in combination.

[0049] In the copolymer (1), the content of the constituting units
corresponding to the cationic vinyl monomer (A) is preferably at least 10
wt %, more preferably at least 20 wt %, further preferably at least 25 wt
% and preferably at most 80 wt %, more preferably at most 70 wt %,
further preferably at most 60 wt %. Such constituting units corresponding
to the cationic vinyl monomer (A) are considered to form, when an anionic
surfactant is used in combination in the cosmetic composition, a complex
therewith thereby to let the copolymer (1) readily deposit on the hair.
By adjusting the constituting units corresponding to the cationic vinyl
monomer (A) to be at least 10 wt %, it is possible to form a more
sufficient complex with the anion surfactant and sufficiently maintain
the strength of adsorption to the hair or the like, and by adjusting them
to be at most 80 wt %, it is possible to formulate a cosmetic composition
without bringing about aggregation, such being desirable.

[0050] The nonionic vinyl monomer (B) is not particularly limited so long
as it is one represented by the following formula (II) or (III), and it
is effective to impart hydrophilicity to the copolymer (1) due to the
hydrophilicity derived from the nonionic vinyl monomer (B). It is
considered that the solubility of the copolymer (1) in water is thereby
improved, and also at the time when the copolymer (1) forms a complex
with the surfactant, the solubility of the copolymer in water can be
maintained. As the nonionic vinyl monomer (B), it is preferred to use two
or more types of either one of the following formulae (II) and (III) in
combination, and it is particularly preferred to use ones of the formulae
(II) and (III) in combination.

CH2═C(R8)--CO(O)--X--H (II)

(wherein R8 is a hydrogen atom or a methyl group, and X is a
bivalent linking group containing at least two hydroxy groups)

CH2═C(R9)--CO--NR19R11 (III)

(wherein R9 is a hydrogen atom or a methyl group, and each of
R19 and R11 which are independent of each other, is a hydrogen
atom, a C1-4 alkyl group or a C1-4 hydroxyalkyl group).

[0051] The nonionic vinyl monomer represented by the formula (II) is not
particularly limited, so long as it is one included in this formula.
However, it is preferred that X is a bivalent linking group which is a
linking group having from 2 to 9 carbon atoms and containing at least two
hydroxy groups, which may contain an oxygen atom and/or a nitrogen atom.
More preferably, X is a bivalent linking group containing at least two
hydroxy groups, which is represented by
{--(CH2)c--(CR12R13)d--(CHOH)e--(CH2O)-
f--}, wherein each of R12 and R13 which are independent of
each other, is a C1-3 alkyl group or a C1-3 hydroxyalkyl group,
c is an integer of from 1 to 4, d is 0 or 1, e is an integer of from 1 to
6, and f is an integer of from 0 to 2. Here, the order of four types of
linking groups i.e. --(CH2)--, --(CR12R13)--, --(CHOH)--
and --(CH2O)-- in {} is optional, and they may be present at random.
For example, in a case where c is 2, d 0, e 1 and f 0, the structure in
{} may be {--(CH2)--(CH2)--(CHOH)--} or
{--(CH2)--(CHOH)--(CH2)--}. Particularly preferably, X is a
bivalent linking group containing at least two hydroxy groups, which is
represented by {--(CH2)c--(CHOH)e--},
{--(CH2)c--(CR12R13)--(CHOH)--} or
{--[(CH2)--(CHOH)--(CH2O)]g--}, wherein R12, R13
and c to f are as defined above, and g is an integer of from 1 to 3.

[0053] In the nonionic vinyl monomer represented by the formula (III),
R9 is preferably a hydrogen atom. Each of R10 and R11
which are independent of each other, is preferably a hydrogen atom, a
C1-4 alkyl group or a C1-4 hydroxyalkyl group. The C1-4
alkyl group or the C1-4 hydroxyalkyl group may, for example, be a
methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl
group, an isobutyl group, a hydroxymethyl group or a 2-hydroxyethyl
group. The sum of the numbers of carbon atoms in R10 and R11 is
preferably from 2 to 4, most preferably 2. a is preferably an integer of
from 1 to 3, most preferably 2.

[0054] The nonionic vinyl monomer represented by the formula (III) is not
particularly limited so long as it is included in this formula, and it
may, for example, be an alkylacrylamide such as N-methyl
(meth)acrylamide, N-ethyl (meth)acrylamide, N-propyl (meth)acrylamide or
N-isopropyl (meth)acrylamide; a dialkylacrylamide such as N,N-dimethyl
(meth)acrylamide or N,N-diethyl (meth)acrylamide; or a hydroxyalkyl
(meth)acrylamide such as N-hydroxymethyl (meth)acrylamide,
N-(2-hydroxyethyl) (meth)acrylamide, N,N-bis(hydroxymethyl)
(meth)acrylamide or N,N-bis(2-hydroxyethyl) (meth)acrylamide.

[0055] One of such nonionic vinyl monomers (B) may be used alone, or two
or more of them may be used in combination. It is preferred to employ the
nonionic vinyl monomer represented by the formula (II), since the metal
pyrithione salt persistence in the cosmetic composition is further
improved.

[0056] The content of the structural units corresponding to the nonionic
vinyl monomer (B) in the copolymer is preferably at least 20 wt %, more
preferably at least 30 wt %, further preferably at least 40 wt % and
preferably at most 90 wt %, more preferably at most 80 wt %, further
preferably at most 75 wt %. By adjusting the structural units
corresponding to the nonionic vinyl monomer (B) to be at least 20 wt %,
the solubility of the copolymer (1) in water becomes high, and it becomes
possible to maintain sufficient solubility in water even when, for
example, it forms a complex with an anionic surfactant. Further, it is
preferred to adjust them to be at most 90 wt %, so as to maintain the
complex with the anionic surfactant.

[0057] In the copolymer (1), structural units derived from another vinyl
monomer may further be contained. However, if an anionic functional group
is present in the copolymer (1), such may hinder the formation of the
complex especially when an anionic surfactant is employed, and
accordingly, one containing little anionic functional group is preferred
(for example, at most 10% in all functional groups), and one not
substantially containing it, is more preferred. Here, not substantially
containing is meant for one showing no anionic property e.g. at a pH of
from 3 to 8.

[0058] Such another vinyl monomer may, for example, be a nonionic monomer
such as an ester of a C1-22 alcohol with (meth)acrylic acid, an
amide of a C1-22 alkylamine with (meth)acrylic acid, a monoester of
ethylene glycol or 1,3-propylene glycol with (meth)acrylic acid, an ester
having a hydroxy group of such a monoester etherified with e.g. methanol
or ethanol, (meth)acryloylmorpholine, hydroxymethylacrylamide, or
hydroxyethylacrylamide; an amino acid-type cationic monomer such as a
diallyl type quaternary ammonium salt such as
N,N-dimethyl-N,N-diallylammonium chloride, or a reaction product of
L-arginine with glycidyl methacrylate; an amphoteric monomer such as a
betaine group-containing (meth)acrylester, or a betaine group-containing
(meth)acrylamide; or a semipolar monomer such as an amineoxide
group-containing (meth)acrylester, or an amineoxide group-containing
(meth)acrylamide.

[0059] The content of the structural units derived from another vinyl
monomer in the copolymer (1) may suitably be determined within a range
not to depart from the concept of the present invention. For example, it
may be suitably determined within a range not to impair the solubility as
the water-soluble resin or not to impair the conditioning effect in a
case where it is used for a cosmetic composition for the hair. Usually,
it is preferably at most 30 wt %, more preferably at most 20 wt %, in the
copolymer (1).

[0060] The contents of the constituting units corresponding to the
cationic vinyl monomer (A), constituting units corresponding to the
nonionic vinyl monomer (B) and the constituting units derived from
another vinyl monomer, in the copolymer (1), can be obtained from the
amounts of the respective monomers used. However, they can also be
obtained by measuring IR absorption of a hydroxy group or an amide bond
moiety, 1H-NMR of a hydroxy group or an amide bond moiety, or a
methyl group adjacent to a cation group, or 13C-NMR thereof.

[0061] The copolymer (1) to be used in the present invention preferably
has a solubility in water to such an extent that it is capable of forming
an aqueous solution having a concentration of at least 5 wt % at room
temperature i.e. at 25° C. That is, it is preferably a
water-soluble resin such that its aqueous solution at a concentration of
at least 5 wt % has a transmittance to water at a wavelength of 550 nm
being at least 80%, and the aqueous solution is uniform and stable. More
preferred is one capable of forming an aqueous solution having a
concentration of at least 20 wt %.

[0062] The copolymer (1) of the present invention can be produced, for
example, by mixing monomers to present the respective constituting units,
or their precursors, and copolymerizing them by a method such as solution
polymerization, suspension polymerization or emulsion polymerization,
followed by cationization reaction as the case requires.

[0063] The polymerization reaction is preferably carried out in water
and/or a hydrophilic solvent. The hydrophilic solvent may, for example,
be a ketone solvent such as acetone, methyl ethyl ketone or methyl
isobutyl ketone; or an alcohol solvent such as methanol, ethanol,
n-propanol, i-propanol, n-butanol, i-butanol or sec-butanol. Such water
and/or a hydrophilic solvent may be used alone, or two or more of them
may be used in combination. It is particularly preferred to employ an
alcohol solvent or water.

[0064] For the polymerization reaction, a polymerization initiator may be
used. As the polymerization initiator, an azo compound such as
2,2'-azobisisobutyronitrile,
2,2'-azobis(2-methyl-N-(2-hydroxyethyl)-propionamide),
2,2'-azobis(2,4-dimethylvaleronitrile),
2,2'-azobis(4-methoxy-2,4-dimethylvaleronitrile),
dimethyl-2,2'-azobisisobutyrate, 2,2'-azobis(2-methylbutyronitrile),
1,1'-azobis(1-cyclohexanecarbonitrile),
2,2'-azobis(2-methyl-N-(2-hydroxyethyl)-propionamide) or
2,2'-azobis(2-amidinopropane)dihydrochloride, a peroxide such as benzoyl
peroxide, dicumyl peroxide, di-t-butyl peroxide or lauroyl peroxide, a
persulfate, or its redox may, for example, be used without any particular
restriction. The polymerization initiator is used preferably within a
range of from 0.01 to 5 wt %, more preferably within a range of from 0.1
to 3 wt %, based on all monomers.

[0065] The polymerization reaction can be carried out, for example, in an
inert gas atmosphere such as nitrogen or argon, preferably at a
temperature of from 30 to 120° C., more preferably from 40 to
100° C., usually for from 1 to 30 hours. After completion of the
polymerization, the formed copolymer is preferably isolated from the
reaction solution by a suitable means such as distillation of the solvent
or addition of a poor solvent. The obtained copolymer (1) may be used as
it is or after purifying it, for the preparation of the cosmetic
composition of the present invention. The purification may be carried out
by suitable means such as reprecipitation, washing with a solvent,
membrane separation, etc. in combination, as the case requires.

[0066] As the copolymer (1) to be used in the present invention, it is
possible to utilize one having an optional structure such as a random
copolymer, a block copolymer or a graft copolymer, without any particular
restriction.

[0067] The random copolymer can be prepared, for example, by a method of
adding an initiator to a mixture of all monomers to be used for the
polymerization thereby to react them all at once, or a method of
gradually reacting them while dropwise adding a part or all amount of the
monomers. It is also possible to carry out the polymerization by dropwise
adding the monomers while changing the monomer composition. The block
copolymer can be prepared by utilizing e.g. a known radical initiator or
catalyst. The graft copolymer can be prepared by a method of utilizing a
macromer having a vinyl functional group or a method of reacting polymers
having reactive functional groups to each other.

[0068] Among them, one which can be prepared from an inexpensive raw
material without requiring a special step, is preferred with a high
industrial applicability, and a random copolymer is most preferred which
can be most easily prepared by using a usual raw material.

[0069] Further, at the time of formulating the copolymer (1) into a
cosmetic composition, a plurality of copolymers may be used in
combination. In such a case, copolymers may be separately prepared and
then mixed and formulated. Otherwise, one copolymer is firstly prepared,
and in the reaction liquid, a monomer component to constitute another
copolymer is added and polymerized to obtain a mixture of two copolymers.
Likewise, by repeating addition and polymerization of a monomer
component, it is possible to obtain a mixture of more copolymers. In the
present invention, the latter method is preferred whereby the mixture can
be simply prepared.

[0070] The weight average molecular weight of the copolymer (1) is
preferably from 10,000 to 2,000,000. By adjusting the weight average
molecular weight to be at least 10,000, it is possible to improve the
metal pyrithione salt delivery effect especially at the time of using an
anion surfactant, by deposition of a complex formed with the anion
surfactant on the hair or skin. The weight average molecular weight is
more preferably at least 100,000, further preferably at least 200,000. By
adjusting it to be at most 2,000,000, it is possible to maintain the
viscosity of the copolymer (1) solution to be proper, whereby the
formulation property is improved, and the handling efficiency for the
production will be facilitated. The weight average molecular weight of
the copolymer (1) can be measured by gel permeation chromatography (using
e.g. water/methanol/acetic acid/sodium acetate as a developing solvent)
and can be determined by using polyethylene glycol as a standard
substance. It is more preferably at most 1,000,000, further preferably at
most 700,000.

[0071] The viscosity of the copolymer (1) solution is preferably within a
proper range, for example, at a level where a 20 wt % aqueous solution of
the copolymer (1) can be prepared. The viscosity of the 20 wt % aqueous
solution at 25° C. is more preferably at most 100,000 mPas,
further preferably at most 50,000 mPas, still further preferably at most
20,000 mPas, most preferably at most 5,000 mPas. However, it is usually
at least 10 mPas. That is, at a high concentration, transportation as a
product is facilitated.

[0072] The viscosity can be adjusted by controlling the polymerization
degree of the copolymer (1). Further, the molecular weight and viscosity
can be controlled also by adding a crosslinking agent such as a
polyfunctional acrylate or by increasing or decreasing the amount of its
addition. However, if the crosslinking agent is added excessively even to
a small extent, it may become difficult to control the molecular weight
and viscosity for the industrial production, as the molecular weight and
viscosity are likely to abruptly increase. If the molecular weight and
viscosity become too high, the formulation property will be deteriorated
as mentioned above, such being undesirable. Therefore, the amount of the
crosslinking agent to be used is preferably controlled to be an amount
within a range where the molecular weight will not increase at the time
of the polymerization. For example, it is at most 0.1 wt %, more
preferably at most 0.01 wt %, to the amount of the copolymer (1). Most
preferably, a crosslinking agent is not used at the time of the
polymerization of the copolymer (1), and no crosslinking agent is
contained as a constituting component of the copolymer (1).

[0073] As a method for controlling the molecular weight of a copolymer
(1), a method of using a chain transfer agent at the time of the
polymerization may be mentioned. By an addition of a chain transfer
agent, it is possible to lower the molecular weight. However, there may
be a case where control becomes difficult in an industrial production,
such that if the added amount is too much, the molecular weight tends to
be too low. Further, a thiol which is commonly used as a chain transfer
agent, such as thioglycol, an alkylthiol or thioglycolic acid, has such a
demerit that it causes deterioration of the odor. Accordingly, it is
preferred not to contain a chain transfer agent.

[0074] The content of the copolymer (1) in the cosmetic composition of the
present invention is not particularly limited, and a suitable amount may
be used depending upon its application. Particularly in the case of a
hair-wash, the content is preferably from 0.05 to 2 wt %, more preferably
at least 0.1 wt %, further preferably at least 0.2 wt %, in the
composition.

<Metal Pyrithione Salt>

[0075] The cosmetic composition of the present invention further contains
a metal pyrithione salt in addition to the polymer of the present
invention. The metal pyrithione salt has an antibacterial effect, and
when it is incorporated to a cosmetic composition, it exhibits an
anti-dandruff effect. By using e.g. a hair wash having the metal
pyrithione salt incorporated, it is permitted to stay on the hair to
exhibit such an effect, and the more the residual amount, the higher the
anti-dandruff effect. In the cosmetic composition of the present
invention, the metal pyrithione salt is blended with the polymer of the
present invention, whereby it is possible to realize an excellent metal
pyrithione salt persistence on the hair, skin, etc. after the use of the
cosmetic composition.

[0076] In the first embodiment of the present invention, when the cosmetic
composition of the present invention is used as a hair wash, the amount
of adsorption of the metal pyrithione salt is usually at least 20 μg/g
on at least one of untreated hair and damaged hair. And, depending upon
the type of the polymer (or the types and combination of monomers as raw
materials for the polymer), the combination, etc. constituting the
cosmetic composition, the amount of adsorption is preferably at least 30
μg/g, more preferably at least 40 μg/g, further preferably at least
65 μg/g.

[0077] Further, the present invention places more emphasis on the metal
pyrithione salt adsorption effect on untreated hair than on damaged hair.
Accordingly, upon satisfying the amount of adsorption of the metal
pyrithione salt being at least 65 μg/g on at least one of untreated
hair and damaged hair, the amount of adsorption on untreated hair is more
preferably at least 65 μg/g, particularly preferably at least 180
μg/g, most preferably at least 295 μg/g. Further, the amount of
adsorption of the metal pyrithione salt which can be accomplished by the
construction of the present invention is at a level of 2,000 μg/g on
each of untreated hair and damaged hair.

[0078] Here, the reason as to why emphasis is placed particularly on the
amount of adsorption of the metal pyrithione salt on untreated hair in
the present invention, is as follows. The anti-dandruff agent represented
by the metal pyrithione salt, particularly zinc pyrithione, is one
exhibiting the effect by killing bacteria. Accordingly, it is preferred
that the anti-dandruff agent is adsorbed in a substantial amount at the
portion close to the scalp. In general, the hair at the portion close to
the scalp is healthy hair, and the hair at the portion remote from the
scalp is one physically damaged by e.g. heat or ultraviolet ray. With
respect to untreated hair and damaged hair in the present invention,
untreated hair rather than damaged hair is in a healthy hair state close
to the scalp, and therefore, the amount of adsorption of the metal
pyrithione salt on untreated hair is emphasized than on damaged hair.
Here, the method for evaluating the amount of adsorption of the metal
pyrithione salt on untreated hair and damaged hair is as follows.

(Evaluation Method)

[0079] A hair wash is applied to a prepared hair bundle, and then, the
amount of adsorption of the metal pyrithione salt on the hair is
quantitatively determined. The hair bundle to be used is as "untreated
hair" "human black hair (100%) bundled at the root (untreated hair: 10
g×30 cm); manufactured by Beaulax". Further, as "damaged hair", one
having the "untreated hair" subjected to bleach treatment is used. Here,
bleach treatment is carried out in such a manner that as the bleaching
agent, a mixture comprising 12 g of Promatiz Flaeve oxytan 6.0 (6%
hydrogen peroxide cream) manufactured by Milbon Co., Ltd. and 26 g of
Powder Bleach MR manufactured by Meros Chemical Company, is applied to
one hair bundle and left to stand for 30 minutes, followed by washing
with water, and further, polyoxyethylene (3) lauroyl ether sodium sulfate
is applied, followed by washing.

(Amount of Adsorption of Metal Pyrithione Salt)

[0080] About 10 g of the hair bundle is wet with running water of
40° C. for 30 seconds and then drained off until water droplets
will no longer drop, whereupon 1 g of the hair wash is applied and
bubbled by running a comb through the hair 100 times per minute. The hair
bundle is rinsed with running water at 40° C. for 30 seconds and
then dried overnight at a temperature of 23° C. under a humidity
of 60%. Thereafter, the hair bundle is immersed for two minutes in a 0.5N
potassium hydroxide methanol/water (4/1 (weight ratio)) solution to
extract zinc pyrithione adsorbed on the hair thereby to obtain an extract
solution. The amount of adsorption of the metal pyrithione salt is
evaluated by the absorbance determination (288 nm) of the extract
solution. A calibration curve is preliminarily prepared by a plurality of
standard samples having different concentrations by dissolving the metal
pyrithione salt in a 0.5N potassium hydroxide (KOH) methanol/water (4/1
(weight ratio)) solution, and the amount of adsorption is determined from
the measured absorbance of the extract solution and the calibration
curve. Here, a blank in the absorbance determination is an extracted
solution obtained by immersing "untreated hair" in a 0.5N KOH
methanol/water (4/1 (weight ratio)) solution for two minutes. Further,
the amount of adsorption of the metal pyrithione salt is calculated as
the amount of adsorption of the metal pyrithione salt per unit weight of
the hair by preliminarily measuring the weight of each hair bundle.

[0081] In a case where the cosmetic composition of the present invention
is used as a hair wash, a high adsorption of the metal pyrithione salt on
the hair is shown, because the copolymer has a cationic group amount and
an amide group amount capable of precipitating a precipitate having a
high persistence on the hair, or the copolymer contains a structure to
increase the mutual action between the precipitate and the metal
pyrithione salt.

[0082] The reason for the improvement of the metal pyrithione salt
persistence by the combined use of the polymer of the present invention
and the metal pyrithione salt, is not clearly understood, but it is
considered that the polymer of the present invention improves the
dispersibility of the metal pyrithione salt, and when an anion surfactant
is used, the cationic polymer or the copolymer (1) will form a complex
with e.g. the anion surfactant, which will also act on the metal
pyrithione salt at the time of deposition on the hair or skin thereby to
provide an effect to promote deposition of the metal pyrithione salt on
the hair or skin or to prevent it from being washed off, whereby the
metal pyrithione salt persistence will be improved.

[0083] The metal pyrithione salt is not particularly limited, but it is
preferably a pyrithione salt of zinc, tin, cadmium, magnesium, aluminum
or zirconium. Among them, zinc pyrithione (zinc
bis-[1-hydroxy-2(1H)-pyridinethionate]) as a pyrithione salt of zinc is
particularly preferred.

[0084] The blend proportion of the metal pyrithione salt in the cosmetic
composition of the present invention varies depending upon the function
to be imparted to the composition, but, it may, for example, be
preferably from 0.05 to 2 wt %, based on the entire composition.

<Anion Surfactant>

[0085] Further, it is preferred to further incorporate an anion surfactant
to the cosmetic composition of the present invention in order to more
effectively utilize the residual effect of the metal pyrithione salt in
the cosmetic composition.

[0086] The amount of the anion surfactant to be used is usually from 1 to
25 wt %, preferably from 5 to 20 wt %. If the amount is less than 1 wt %,
the washing function may be impaired when used as a washing liquid. On
the other hand, if it exceeds 25 wt %, the viscosity of the washing
liquid may be hardly increased, or formation of the precipitate may be
impaired.

[0087] As such an anion surfactant, one commonly used in a washing liquid
composition, may be used such as an α-olefin sulfonate, a higher
alcohol sulfuric acid ester salt, a polyoxyethylene alkyl ether sulfuric
acid ester salt, a paraffin sulfonate, a polyoxyethylene alkyl ether
carboxylate, an alkylsulfosuccinate, an N-acyl-β-alanine salt, an
N-acyl glutamate or an acyl methyl taurine salt. A counter ion of such an
anion surfactant may, for example, be sodium, potassium, ammonium,
triethanolamine or diethanolamine. Further, a plurality of anion
surfactants may be used in combination.

<Optional Components>

[0088] To the cosmetic composition of the present invention, in addition
to the above components, components capable of being commonly blended to
cosmetics may optionally be incorporated. Such other components to be
incorporated to the cosmetic composition are not particularly limited and
may be blended within a range not to impair the object or effects of the
present invention. As such components, the following may be mentioned,
and in addition to the cationic polymer or the copolymer (1), and the
metal pyrithione salt, the following components may suitably be blended
to prepare the cosmetic composition of the present invention.

[0089] A water-soluble polymer may, for example, be methylcellulose or
hydroxymethylcellulose. Further, an anionic polymer may, for example, be
an acrylic acid derivative (such as a polyacrylic acid or its salt, or an
acrylic acid/acrylamide/ethyl acrylate copolymer or its salt), a
methacrylic acid derivative or a crotonic-acid derivative; a nonionic
polymer may, for example, be an acrylic acid derivative (such as a
hydroxyethyl acrylate/methoxyethyl acrylate copolymer or a
polyacrylamide), or a vinyl pyrrolidone derivative (such as a
polyvinylpyrrolidone or a vinylpyrrolidone/vinyl acetate copolymer); and
an amphoteric polymer may, for example, be dimethyldiallylammonium
chloride derivative (such as an acrylamide/acrylic
acid/dimethyldiallylammonium chloride copolymer, or an acrylic
acid/dimethyldiallylammonium chloride copolymer). These additional
components may preferably be contained in an amount of from 0.1 to 1 wt %
in the cosmetic composition.

[0090] The amphoteric surfactant may, for example, be an imidazoline type
amphoteric surfactant such as sodium
2-undecyl-N,N,N-(hydroxyethylcarboxymethyl)-2-imidazoline, or
2-cocoyl-2-imidazolinium hydroxide-1-carboxyethyloxy disodium salt; or a
betaine type surfactant such as
2-heptadecyl-N-carboxymethyl-N-hydroxyethyl imidazolinium betaine,
lauryldimethylamino succinic acid betaine, an alkylbetaine, an
amidebetaine or a sulfobetaine.

[0095] As other components, a natural extract from animals and plants or
its derivatives, an organic acid such as citric acid or lactic acid, an
inorganic salt such as sodium chloride, an amino acid (such as glutamic
acid or its salts, arginine or its salts or glycine), a solubilizing
agent (such as ethanol, isopropanol or butanol), a polyhydric alcohol
(such as ethylene glycol, polyethylene glycol, propylene glycol,
dipropylene glycol, polypropylene glycol, 1,3-butylene glycol, glycerol,
diglycerol or isoprene glycol), sugar (such as sorbitol, maltitol,
xylitol, glucose, fructose, mannitol or inositol), a high molecular
weight substance such as hyaluronic acid, an antioxidant, an ultraviolet
absorber, a fungicide, an antiseptic, a chelating agent, a flagrance, a
coloring agent, a higher fatty acid, a thickener, a metal-sealing agent
(such as an edetate), a pH-controlling agent, a foaming promoter, etc.
may suitably be incorporated within a range not to impair the effects of
the present invention.

EXAMPLES

[0096] Now, specific embodiments of the present invention will be
described in further detail with reference to Examples and Comparative
Examples, but it should be understood that the present invention is by no
means restricted by such Examples.

<Evaluation Method>

[0097] A hair wash was applied to a prepared hair bundle, and then, the
amount of adsorption of the zinc pyrithione on the hair was
quantitatively determined. The hair bundle to be used was as "untreated
hair" "human black hair (100%) bundled at the root (untreated hair: 10
g×30 cm); manufactured by Beaulax". Further, as "damaged hair", one
having the "untreated hair" subjected to bleach treatment was used. Here,
bleach treatment was carried out in such a manner that as the bleaching
agent, a mixture comprising 12 g of Promatiz Flaeve oxytan 6.0 (6%
hydrogen peroxide cream) manufactured by Milbon Co., Ltd. and 26 g of
Powder Bleach MR manufactured by Meros Chemical Company, was applied to
one hair bundle and left to stand for 30 minutes, followed by washing
with water, and further, polyoxyethylene (3) lauroyl ether sodlium
sulfate was applied, followed by washing.

<Amount of Adsorption of Zinc Pyrithione>

[0098] About 10 g of the hair bundle was wet with running water of
40° C. for 30 seconds and then drained off until water droplets
would no longer drop, whereupon 1 g of the hair wash was applied and
bubbled by running a comb through the hair 100 times per minute. The hair
bundle was rinsed with running water at 40° C. for 30 seconds and
then dried overnight at a temperature of 23° C. under a humidity
of 60%. Thereafter, the hair bundle was immersed for two minutes in a
0.5N potassium hydroxide methanol/water (4/1 (weight ratio)) solution to
extract zinc pyrithione adsorbed on the hair thereby to obtain an extract
solution. The amount of adsorption of the zinc pyrithione was evaluated
by the absorbance determination (288 nm) of the extract solution. A
calibration curve was preliminarily prepared by a plurality of standard
samples having different concentrations by dissolving the zinc pyrithione
in a 0.5N potassium hydroxide (KOH) methanol/water (4/1 (weight ratio))
solution, and the amount of adsorption was determined from the measured
absorbance of the extract solution and the calibration curve. Here, a
blank in the absorbance determination was an extracted solution obtained
by immersing "untreated hair" in a 0.5N KOH methanol/water (4/1 (weight
ratio)) solution for two minutes.

[0099] Further, the amount of adsorption of the zinc pyrithione was
calculated as the amount of adsorption of the zinc pyrithione per unit
weight of the hair by preliminarily measuring the weight of each hair
bundle.

[0101] The copolymer (i) was formed into a 20 wt % aqueous solution, and
the viscosity was measured at 25° C. by means of a B-type
viscometer and using rotor No. 2 at 30 rpm.

Example 1

(Preparation of Copolymer (i))

[0102] Into a reactor equipped with a reflux condenser, a dropping funnel,
a thermometer, a nitrogen gas-introducing tube and a stirring device, 200
parts by weight of distilled water was charged, and a monomer mixture
solution comprising 43 parts by weight of
N-methacryloyloxyethyl-N,N,N-trimethylammonium chloride (DMC) as the
cationic vinyl monomer (A), 57 parts by weight of
N-hydroxyethylacrylamide (HEAA) as the nonionic vinyl monomer (B) and 100
parts by weight of distilled water, was charged into the dropping funnel.
After substitution with nitrogen, the reactor was heated to 90° C.
After introducing 0.5 part by weight of
2,2'-azobis(2-methyl-N-(2-hydroxyethyl)-propionamide) into the reactor,
the monomer mixture solution was dropwise added from the dropping funnel
over a period of 4 hours. After completion of the dropwise addition, the
reaction was continued at 90° C. for 20 hours, followed by cooling
to obtain a copolymer (i).

[0103] Of the obtained copolymer (i), the ratio of the constituting units
corresponding to the respective monomers in the total constituting units
was DMC/HEAA=43/57 (wt %), the weight average molecular weight was
370,000, the viscosity was 550 mPas, the amount of the cationic group was
2.07 meq/g, and the amount of the hydroxy group was 4.95 meq/g.

[0104] The results are shown in Table 1.

(Preparation of Hair Wash)

[0105] Using the copolymer (i) obtained by the above method, a hair wash
having the composition shown in Table 2, was prepared. The numerical
values in the Table are weights (parts by weight) of the respective
components.

(Evaluation of Cosmetic Composition)

[0106] Using the hair wash prepared by the above method, the amount of
adsorption of zinc pyrithione on the hair (untreated hair and damaged
hair) was measured, and the zinc pyrithione salt persistence was
evaluated. The evaluation results are shown in Table 2.

Examples 2 to 6 and Comparative Example 1

[0107] (Preparation of Copolymers (ii) to (vii))

[0108] Copolymers (ii) to (vii) were, respectively, prepared in the same
manner as in the preparation of the copolymer (i) except that monomers
disclosed in the monomer compositions in Table 1 were used. The weight
average molecular weight, the viscosity, the amount of the cationic
group, the amount of the hydroxy group and the amount of the amide group,
of the obtained copolymer are shown in Table 1. Here, the ratio of
constituting units corresponding to the respective monomers in the total
constituting units is the same as the ratio (wt %) of the respective
monomers being raw materials for each copolymer shown in Table 1.

[0109] Further, one wherein a copolymer (v) was used, is Comparative
Example 1.

(Preparation and Evaluation of Hair Wash)

[0110] The preparation and evaluation of a hair wash were carried out in
the same manner as in Example 1 except that the copolymers (ii) to (vii)
were used. The composition and evaluation results of each hair wash are
shown in Table 2.

Comparative Example 2

(Preparation and Evaluation of Hair Wash)

[0111] The preparation and evaluation of a hair wash were carried out in
the same manner as in Example 1 except that cationated
hydroxyethylcellulose (JR400, manufactured by Calgon) was used instead of
the copolymer (i). The composition and evaluation results of the hair
wash are shown in Table 2.

Comparative Example 3

(Preparation and Evaluation of Hair Wash)

[0112] The preparation and evaluation of a hair wash were carried out in
the same manner as in Example 1 except that a cation-modified guargum
(Jaguar C13S, manufactured by Rohm) was used instead of the copolymer
(i). The composition and evaluation results of the hair wash are shown in
Table 2.

[0113] 1) From the results of the amount of adsorption of zinc pyrithione
shown in Table 2, Examples 1 to 4 exhibited high adsorption on the
untreated hair or damaged hair. Further, especially, Examples 5 and 6
exhibited high adsorption on both the untreated hair and damaged hair.

[0114] 2) In Comparative Example 1, zinc pyrithione was not adsorbed on
the untreated hair or damaged hair even though N-hydroxyethylmethacrylate
was used as a nonionic vinyl monomer for the production of the copolymer.

[0115] 3) In Comparative Example 2, the zinc pyrithione adsorption on the
untreated hair and damaged hair was poor even though a cationated
hydroxyethylcellulose was used as a water-soluble resin instead of the
copolymer of the present invention.

[0116] 4) In Comparative Example 3, the zinc pyrithione adsorption on the
untreated hair and damaged hair was poor even though a cationated guargum
was used as a water-soluble resin instead of the copolymer of the present
invention.

INDUSTRIAL APPLICABILITY

[0117] The cosmetic composition of the present invention is excellent
particularly in the metal pyrithione salt persistence after washing with
a washing liquid containing a surfactant, etc., whereby it is possible to
exhibit a sufficient anti-dandruff effect by using only a small amount of
a metal pyrithione salt.

[0118] Particularly in a case where the cosmetic composition of the
present invention is used as a washing liquid, it is excellent in both
the washing property to remove dirt such as oil or dust on the body, hair
or scalp and the anti-dandruff effect, and it is possible to present a
washing liquid which exhibits a good touch such as smoothness after the
use. Thus, it can be used particularly suitably as a hair wash.

[0119] The entire disclosure of Japanese Patent Application No.
2009-038093 filed on Feb. 20, 2009 including specification, claims,
drawings and summary is incorporated herein by reference in its entirety.

Patent applications by MITSUBISHI CHEMICAL CORPORATION

Patent applications in class Hetero ring is six-membered consisting of one nitrogen and five carbons

Patent applications in all subclasses Hetero ring is six-membered consisting of one nitrogen and five carbons